South West Water has revealed it plans to invest £850 million between 2015 and 2020 as it launches a consultation on its draft business plan.

Projects part of the investment include a £50 million-plus new water treatment works in Plymouth, which will use a new energy-saving process not used in the UK before, more renewable energy generation capability and the construction of flood defence around key sites so water services to homes and businesses are maintained during extreme weather.

The company’s award-winning Upstream Thinking programme to restore wetlands will be expanded while bathing water will be better protected through an improved sewerage network.

Customers are now being asked to comment on its draft WaterFuture proposals in which South West Water has divided its proposals into eight themed investment areas ranging from 'Ensuring the region has the water it needs' to 'Value for money charging and helping those in need' following consultation earlier in the year.

For the first time, the company is also revealing how future bills in 2020 might add up depending on how much is invested in each area, what efficiency savings it can deliver and future inflation rates.

Currently it is recommending investment which may lead to below inflation bill increases of around 2.5% per year - or an overall £68 increase in the average annual household water and sewerage bill between 2015 and 2020.

South West Water forecasts an average annual water and sewerage bill in 2020 of approximately £588 based on its recommended proposals.

Chief Executive Chris Loughlin said:

"We still need to invest in our networks to maintain the achievements of the past such as reduced leakage rates, record tap water quality and transformed bathing waters.

"There are also new challenges to face including population growth, the likelihood of more extreme weather and higher bathing water standards from 2015. Our aim is to invest in the right things at the right time to both improve our services and give the region the reliable 'always there' infrastructure it needs.

"In some areas like water resources, we don't need to invest in expensive new reservoirs. However, in other areas such as our programme to improve raw water quality on the moors, if we don't invest sooner rather than later we could end up facing much higher costs in the future.

"We believe we are close to striking the right balance between the needs of customers, the environment and the economy. Although no one likes to see bills increase, we should be able to keep future increases below the rate of inflation.

"However, before we finalise our plan in December, we need to hear whether customers think we are getting it right. Should we invest more or less in each area? I urge everyone to get involved in WaterFuture to make sure we do the best job for you."

Customers, groups and organisations have until 14 September to give their feedback on the proposals.